The present invention relates to a process for. preparing certain bridged mono- and bis-cyclopentadienyl metal dihydrocarbyloxy coordination complexes starting from metal hydrocarbyloxide compounds. The present invention also relates to a process for preparing bridged mono- and bis-cyclopentadienyl dihydrocarbyl metal coordination complexes and to a process for preparing bridged mono- and bis-cyclopentadienyl metal dihalide coordination complexes both starting from the corresponding bridged mono- or bis-cyclopentadienyl metal dihydrocarbyloxy coordination complexes.
Bridged mono- and bis-cyclopentadienyl metal dihalide coordination complexes and bridged mono- and bis-cyclopentadienyl dihydrocarbyl metal coordination complexes are known and useful as addition polymerization catalysts or as components or precursors thereof.
In "Metallkomplexe mit verbrueckten permethylierten Cyclopentadienylliganden" of P. Jutzi and R. Dickbreder, Chem. Ber. 119, 1750-1754 (1986) the synthesis is described of dimethylsilanediyl-bridged bis(permethylated cyclopentadienyl) titanium dichlorides from the tetrahydrofuran (THF) adducts of titanium tetrachloride and the dimethylsilanediyl-bridged bis(permethylated cyclopentadienyl) dianion derivatives.
In "ansa-Metallocene derivatives: XVII. Racemic and meso diastereoisomers of group IV metallocene derivatives with symmetrically substituted, dimethylsilanediyl-bridged ligand frameworks. Crystal structure of R,S--Me.sub.2 Si(3--t--Bu--MeC.sub.5 H.sub.2).sub.2 ZrCl.sub.2 " of H. Wiesenfeldt et al., Journal of Organometallic Chemistry, 369 (1989)359-370 the synthesis is described of dimethylsilanediyl-bridged bis(substituted cyclopentadienyl) titanium dichloride complexes from the THF-adducts of titanium trichoride and the dimethylsilanediyl-bridged bis(substituted cyclopentadienyl) dianion derivatives.
In "Synthesis and Complexation of Linked Cyclopentadienyl-Amido Ligands" of J. Okuda, Chem. Ber. 123 (1990) 1649-1651 the preparation is described of a bridged mono(substituted cyclopentadienyl) titanium dichloride complex from the THF-adduct of titanium tetrachloride and the dilithium salt of (tertbutylamino)dimethylsilyl!(tert-butyl)cyclopentadienide.
Bridged mono-cyclopentadienyl metal dihalide coordination complexes are also prepared in U.S. Pat. No. 5,026,798 from titanium tetrachloride compounds or ether adducts thereof and the dilithium salts of bridged mono-cyclopentadienyl ligand compounds.
Further, EP-A-0,416,815 teaches a process to prepare bridged mono-cyclopentadienyl metal dihalide coordination complexes starting from the transition metal tetrahalide and a Group 1 or Grignard derivative of the bridged mono-cyclopentadienyl ligand compounds.
The above-mentioned synthesis methods to prepare the bridged mono- and bis-cyclopentadienyl metal dihalide coordination complexes use metal tetrahalide compounds as starting materials, which are corrosive, toxic, and air and moisture sensitive. In order to facilitate handling thereof, prior to the reaction step the transition metal tetrahalide compound is typically converted to its ether-adduct in a separate step with for example THF or diethyl ether. This adduct formation step in itself proceeds with difficulty, requiring low to very low temperatures, and an inert atmosphere. The adduct is usually recovered before it is reacted with the dianionic derivative of the ligand compound. The yield of the adduct formation step or steps is less than quantitative. Furthermore, the reaction mixture of the transition metal tetrahalide compound and the dianionic derivative of the bridged cyclopentadienyl ligand compound requires a multi-step, laborious recovery and purification procedure. Typically, after the reaction step, the solvent is removed, the product redissolved by adding dichloromethane or toluene or a mixture thereof, the metal halide byproduct, typically lithium chloride, removed by filtration of the mixture, the solvent removed at least partially, followed by redissolving the solid product and crystallizing the product, optionally followed by one or more further recrystallization procedures.
Further, it is known to from EP-A-0,416,815 and EP-A-0,514,828 to prepare bridged mono-cyclopentadienyl metal dihalide coordination complexes, by reacting the THF-adduct of a transition metal trihalide compound, especially TICl.sub.3, with the dianionic derivative of the cyclopentadienyl ligand. The resulting complex is contacted with a non-interfering oxidizing agent, such as for example AgCl (EP-A-0,416,815), or with an organic halide to raise the oxidation state of the metal to form the desired dihalide complex. Apart from requiring an extra reaction step, that is the oxidation step, this process also starts from the transition metal trihalide or an ether-adduct thereof which has the disadvantages listed above, and requires long reaction times to be prepared. Furthermore, the complex resulting from the reaction between the ether adduct of the transition metal trihalide compound with the dianionic derivative of the cyclopentadienyl ligand, i.e. the cyclopentadienyl metal(III) monohalide coordination complex, is thermally unstable.
The bridged mono-cyclopentadienyl dihydrocarbyl metal coordination complexes can be prepared by hydrocarbylating the corresponding bridged mono-cyclopentadienyl metal dihalide coordination complexes with a Grignard, lithium, sodium or potassium salt of the hydrocarbyl ligand. This is described, for example, in EP-A-0,418,044, example 3 and WO 92/00333. These preparation processes inherently have the disadvantages associated with the preparations of the bridged mono-cyclopentadienyl metal dihalide coordination complexes.